<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <style>
    body,
    ul {
      margin: 0;
      padding: 0;
    }
    body {
      width: 1920px;
      height: 1080px;
      box-sizing: border-box;
      border: 3px solid red;

      /* 指定缩放的原点在左上角 */
      transform-origin: left top;
    }
    ul {
      width: 100%;
      height: 100%;
      list-style: none;

      display: flex;
      flex-direction: row;
      flex-wrap: wrap;
    }
    li {
      width: 33.333%;
      height: 50%;
      box-sizing: border-box;
      border: 2px solid green;
      font-size: 30px;
    }
  </style>
  <body>
    <!-- 

     -->
    <ul>
      <li>1</li>
      <li>2</li>
      <li>3</li>
      <li>4</li>
      <li>5</li>
      <li>6</li>
    </ul>
    <script>
      // 设计稿： 1920 * 1080
      // 目标适配：1920 * 1080 3840 * 2160 (2 * 2); 7680 * 2160(4 * 2)

      // 1.设计稿的尺寸
      let targetX = 1920;
      // let targetY = 1080;
      // let targetRatio = 16 / 9; //宽高比率

      // 2.拿到当前设备（浏览器）的宽度
      let currentX =
        document.documentElement.clientWidth || document.body.clientWidth;
      // 1920 * 1080 -> 3840 * 2160

      // 3.计算缩放比例
      let scaleRatio = currentX / targetX; //参照宽度进行缩放

      // 4.开始缩放网页
      document.body.style = `transform: scale(${scaleRatio})`;
    </script>
  </body>
</html>
